Otmir  •■    BftEUfSTE*. 


U.  S.  Department  of  Agriculture.  Forest  Service 

FOREST  PRODUCTS  LABORATORY 

In  cooperation  with  the  University  of  Wisconsin 

MADISON,  WISCONSIN 


CHANGE  IN  MOISTURE  CONTENT  OF 
LUMBER  DURING  RAIL  SHIPMENT 

By  G.  E.  FRENCH 
Assistant  Wood  Technologist 


September,  1927 


t     *    •OTMUMWTT  ntniK*  MTW1     ivn  H — 0O1  h 


change  in  moisture  content  of  lumber 

during  rail  shi?::t:.: 


3y 


G.  E.  French, 
A  •  1st  lit  7ood  Tcchnolo  :ist 


Engineers  are  interested  in  the  degree  of  season- 
ing at  which  standard  sizes  of  lumber  apply,  and  frequently 
also  in  the  possibility  of  obtaining  lumber  of  some  specific 
moisture  content  that  fits  it  for  a  special  use  without  the 
risk  of  changes  in  dimension  due  to  shrinkage  and  swelling. 
It  is  therefore  important  to  know  to  what  extent  the  moisture 
content  of  lumber  changes  during  the  long  rail  hauls  that  are 
now  a  common  necessity  of  lumber  marketing. 

This  paper  presents  the  results  of  an  investiga- 
tion made  to  determine  whether  or  not  lumber  placed  aboard 
cars  at  the  sawmill  at  a  lew  moisture  content  will  change  in 
moisture  content  during  transit  to  such  a  degree  as  to  de- 
feat the  purpose  of  careful  seasoning  for  general  or  soecific 
uses. 

As  a  preliminary  step  in  the  study,  representatives 
of  the  Forest  Products  Laboratory  and  of  the  Forest  Service 
district  products  office,  Missoula  (Kent.,)  early  in  1936 
determined  the  change  in  moisture  content  of  six  carloads  of 
lumber  shipped  from  Idaho  to  the  vicirity  of  Chicago.   The 
late  winter  and  spring  season  was  selected  as  the  time  for 
the  tests  because  this  is  the  period  of  highest  humidity  of 
the  year.   In  the  six  cars  tested  containing  largely  inch 
thick  flat  stock  of  white  fir,  western  yellow  pine,  and  west- 
ern white  pine,  the  moisture  change  of  material  while  in 
transit  was  slight  except  for  some  material  with  30  per  cent 
average  moisture  content  that  lost  about  5  per  cent. 

In  view  of  the  small  changes  which  these  shipments 
showed,  the  Forest  Products  Laboratory  decided  in  1937' to  de- 
termine not  only  the  change  in  average  moisture  content  for 

R836  -1- 


carloads  of  lumber  but  to  show  ir.  wl  ■  -       )rtion  of  the  load 
local  changes,  if  any,  were  taking  piece.   The  cooperatii 
company,  whose  plant  is  located  in  western  Oregon,  was  shi 
ping  clear  grades  of  Douglas  fir  kiln  dried  to  an  average  of 
8  per  cent  moisture  content  and  common  grades  of  Douglas  fir 
kiln  dried  to  approximately  30  per  cent.   Five  cars  of  flat 
clears  were  tested,  one  car  cf  clear  quarter-round  and  crc 
molding,  and  one  car  of  common  shiplap.     hteen  sam- 
boards  were  placed  in  the  same  relative  position  in  each  c 
They  were  protected  from  any  extra  moist  boards  in  the  vi- 
cinity by  being  placed  between  check  boards  of  approximately 
the  si     oisture  content  as  the  sample.   Each  sample  board 
was  sampled  for  moisture  content  and  weighed  to  the  nearest 
hundredth  of  a  pound  at  the  time  it  was  placed  in  the  car. 
At  destination  (Chicago)  the  sample  boards  were  again  weighed 
and  moisture  content  teste  were  made.   As  a  check  upon  these 
two  methods  of  determining  the  change  in  moisture  content  i 
total  weight  of  each  shipment  was  determined  at  the  point  of 
origin  and  destination  by  weighing  the  car  loaded  and  empty. 
The  results  obtained  by  all  three  methods,  na.mely,  (l)  change 
in  weight  of  sample  boards,  (2)  change  in  weight  of  total 
shipment,  and  (3)  change  determined  by  moisture  content  deter- 
minations of  the  samples  at  origin  and  destination,  were  so 
similar  that  only  those  changes  shown  by  the  sample  board 
weights  need  be  considered  her-  . 

The  data,  obtained  are  shown  in  the  accompanying 
table  and  illustrated  graphically  in  the  diagrammatic  cross- 
section  of  the  freight  car.   For  the  five  cars  of  flat  clear 
Douglas  fir  the  average  change  in  moisture  content  was  a 
0.2  per  cent  increase   (based  on  the  oven-dry  weight  of  the 
samples);  for  the  more  loosely  loaded  molding,  0.8  per  cent 
increase;  and  for  the  common  lumber  a  loss  of  0.4  per  cen^ . 
The  changes  were  so  small  as  to  fall  well  within  the  possible 
error  of  moisture  determinations.   The  samples  distributed 
throughout  the  loods  gEve   no  definite  indications  of  local 
changes.   As  all  of  these  shipments  wer?   i  de  from  the  '.Vest 
Coast  two-thirds  of  the  wry  across  the  continent,  with  only 
the  ordinary  precautions  used  in  loading  box  cars  during 
the  wettest  period  of  the  year,  it  is  ouite  reasonable  to 
conclude  that  during  the  usual  haul  in  good  box  errs  no  ap- 
preciable change  in  moisture  content  of  lumber  need  be  ex- 
pected. 

This  information  is  significant.   It  means  that 
stock  placed  in  the  err  in  satisfactory  condition  as  to 
moisture  content  will  reach  the  unloading  point  in  practi- 
cally the  same  condition.   If,  on  the  other  hand,  it  is 

R826  -2- 


received  in  bad  condition  by  the  consignee,  the  fault,  unless 
the  car  is  in  a  poor  state  of  repair,  must  be  with  the  season- 
ing methods  employed. 

The  virtual  elimination  of  this  "unknown'1  between 
shipper  rnd  consignee  brings  the  moisture  content  problem  one 
steo  nearer  solution. 


Change  in  moisture  content  of  Douglas  fir  lumber 
shipped  by  rail  during  the  winter  season  from 
the  West  Coast  to  the  vicinity  of  Chicago. 


Average  : 

Change  in 

j  rload: 

Date   : 

moisture : 

moisture 

shipment : 

Date    : 

reached  : 

Grade   : 

content  : 

content 

No.    : 

shipped  : 

consignee : 

when   : 
loaded  : 

in  transit 

1927    ! 

1927    ; 

Per  cent: 

Per  cent 

1    : 

J^n.  25  : 

Feb.  10  : 

Clears  \ 

8    : 

+  0.2 

2 

,  Feb.   4 

Feb.  28 

it 

8 

+  0.3 

3 

Feb.  10 

Mar.   4 

ii 

10 

t   0.3 

4 

Mar.  18 

Apr.   5 

it 

:   9 

-  0.1 

5 

Mar.  25 

.  Apr.  16 

it 

:    7 

.   -r  0.3 

Av. 

*   #   *   *   a 

k  *  *  *  *  > 

|c    *    *    *    *    J 

"  *  8 

^•0.20 

6 

:  May   5 

:  May  25 

: Quart er- 
: round  and 
:   crown 
: moulding 

:    8 

:   +  0.8 

7 

:  May   6 

:  May  24 

:   Common 

21.0 

:   -  0.4 

: 


-3- 


Digitized  by  the  Internet  Archive 

in  2013 


http://archive.org/details/mrailtureOOfore 


Diagrammatic  cross-section  of  freight 
car  ps  lorded  with  clear  grades  of  Doug- 
las fir.   The  small  rectangles  indicate 
the  location  of  the  srmple  boards  with- 
in load  in  the  1927  tests.   Figures  in 
small  rectangles  show  average  local 
change  in  moisture  content  of  lumber 
during  transit. 


R826 


\-o.i%\ 

+0.3% 

+0.6% 
1 ' 

+0.1% 

+0.2  %>\ 

0.0% 


+0.3% 


-0.1% 


+0.6% 


Average    Chctnc/e    0.2% 


0.0% 


+0.4% 


-0.2% 


0.2% 


0.0% 


+0.3% 


+0.2% 


fA-\  318f 


+0.6% 


+0.5% 


NIVERSITY  OF   FLORIDA 


